But while many are still posting respectable earnings, the guidance is getting more conservative. Specifically, the same-store sales growth isn't as strong as it once was.

Just look at the same-store sales guidance for three of these companies, all of which reported this week:

Zoe's Kitchen

2014: 6.7%

2015 guidance: 4%-6%

Shake Shack

2014: 4.1%

2015 guidance: low single digits

Habit Restaurants

2014: 10.7%

2015 guidance: 2.5%-3.5%

By any definition, that is decelerating same-store sales growth.

This category in general still has the enthusiastic backing of most analysts, but investors have already begun weeding out many of these companies. Potbelly, which went public at the end of 2013, El Pollo Loco, which went public in the middle of last year, and Noodles & Co, which went public in 2013, are all well below their IPO prices.